As will be appreciated from the foregoing literature references, the art has long been appraised of the use of radio-iodine labeled compounds in nuclear medical diagnostic procedures. The art has further been appraised of increasing interest in finding compounds which will effectively cross the blood/brain barrier, thus facilitating more efficacious imaging of the brain.
The compounds of the subject invention facilitate a means whereby a radionuclide is able to efficiently cross the blood/brain barrier. Specifically, the compounds of the present invention facilitate the rapid passage of a radioisotope of iodine, preferably I-123, across the blood/brain barrier. I-123 is preferred because it compares very favorably with I-131 in terms of half-life and absorbed radiation dose.
Because the half-life of I-123 is only 13 hours, it is necessary that procedures in labeling compounds with this radionuclide be both rapid and efficient. It is further necessary, as with any radiolabeled compounds, that the radiolabel, i.e., the iodinecarbon bond in the case of the subject compounds, be stable in vivo with minimal loss of radionuclide from the labeled compound after its administration to the patient. The compounds provided by the present invention satisfy all of these requirements.